1. The Field of the Invention
This invention relates to an information receiving and processing system.
2. State of the Art
Industrial processes are often controlled by computer-based systems. The process control system can include analog to digital converters coupled to sensors which measure various operating parameters of the process. Sensors measure operating parameters and generate analog electrical signals indicative of measured parameters, and analog to digital converters convert the analog signals to digital signals. The digital signals are transmitted to a computer control system which compares the digital signals with target values entered into the control system by an operator via an operator station, and the computer generates digital control signals. The computer control system can include controllers of the so-called proportional, integral, derivative type, i.e. a PID controller. The digital control signals are transmitted to digital to analog converters which convert the signals to analog form, and the analog signals are transmitted to control the process.
Computer-based process control systems of the type discussed above are effective for controlling relatively simple industrial processes. However, for complex industrial processes it is often necessary to interconnect a plurality of PID controllers in cascade fashion so that the signal from one PID controller is processed by at least one additional PID controller. Interconnection of the PID controllers is accomplished by physically wiring the controllers together, which results in a relatively inflexible system since the controllers are, of course, wired in a predetermined configuration which cannot be changed without reconstruction of the system.